redpepper, nycindie: thank you again, your insight was extraordinarily helpful.
The event itself was somewhat underwhelming, but still enjoyable. We liked him, he is nice and we do have things in common. We talked a lot about superficial things and drank way too much.
But, I detected an undercurrent of resentment or anger, which I suppose is not surprising (I don't know him though, this might be normal) and he made one comment in particular that I thought was disrespectful to our lover. I got pretty angry but I bit my lip and we all laughed nervously and blew it off. Later, I found out he apparently felt the situation was forced, which is unfortunate. We were all nervous, but I didn't feel like anyone was insincere.
We did not talk about our situation at all except for one very brief moment, gently initiated by me, during which he was vocal that he does not think he is poly, then we were interrupted. I did not press the issue.
After an evening out, he departed a little early and our girlfriend stayed the night at our house. This did not go over terribly well when he found out, though she did remind him that *he* had chosen to leave, blowing off their previous plans for that night. This was not different than most any other night, but in hindsight maybe it wasn't entirely wise, given the timing.
I am committed to honesty and caring, even with him, but the devil on my shoulder tends to win in these situations when the alternative is the three of us losing time together.
The next day, he retreated a bit more and told our common partner that we were nice but just because we are friends with her does not necessarily mean we are all going to be tight (fair enough). He also has no interest in a relationship with us (this is fine, there was little or no chemistry) and I got the distinct vibe that we should just leave him alone for now. We are concerned that his method of dealing with this is going to be pretending that it's not there. I've been told to give him time, but how much time? Time for what? One positive note, he did say that he wouldn't mind us getting together again, though "not weekly or anything". Better than nothing?
So as of now, things aren't really any different than they were before.